Field of the Invention
The present invention relates to a safety device for a battery or a set of batteries. The invention also relates to a battery suitable for being made safe by means of such a safety device, as well as a set of such batteries. The invention further relates to a method for making such a set of batteries safe.
Prior Art
Batteries are known which are designed based on electrochemical elements of the lithium-ion or nickel-metal hydride type designed to serve as emergency power supplies for low-voltage telecommunication networks. These batteries can be disposed in a modular casing, also called a bay or “rack.” Each bay can contain several batteries each delivering 48 V. A direct current to alternating current power converter (DC/AC) makes it possible to convert the direct current generated by the batteries into alternating current usable for supplying electronic systems of telecommunications networks. It is possible to refer to the site www.saftbatteries.com which gives more information on this type of emergency power supply, in particular the battery systems of the Intensium line.
Such a battery bay is shown in FIGS. 1a and 1b. A bay 40 includes a plurality of identical batteries 42 installed one above the other so that one face 44 of each battery 42 is substantially positioned in the same plane. Referring to FIG. 2, each face 44 includes access to a positive electrical terminal 46 and a negative electrical terminal 48 of a battery 42. The batteries 42 are interconnected by means of electrical connectors 50 so that the electrical connectors 50 connect a positive electrical terminal 46 of one battery 42 to a negative electrical terminal 48 of another battery 42. In particular, the positive electrical terminal 46 of one battery 42 can be connected to an electrical connector 50 at a first connection position A+ or a second connection position B+. Similarly, the negative electrical terminal 48 of a battery 42 can be connected to an electrical connector 50 at a first connection position A− or a second connection position B−. The first connection positions A+ and A− are located on the same side of the battery 42 and the second connection positions B+ and B− are located on the same other side of the battery 42.
The batteries 42 are symmetric so that they can be used reversibly. In other words, the batteries 42 can be positioned in the bay 40 so that the positive 46 and negative 48 electrical terminals are respectively located either on the right and on the left or on the left and on the right of the battery 42.
To reduce the distance between two electrical terminals intended to be connected together by an electrical connector 50 and thus facilitate the interconnection of the batteries 42, the batteries 42 are installed head-to-tail, as can be seen in FIG. 3. In other words, the batteries 42 are positioned in the bay 40 so that a positive electrical terminal 46 of a first battery 42 is positioned facing, or aligned in a direction extending from top to bottom of the bay 40 with respect to, a negative electrical terminal 48 of a second battery 42 positioned above or below the first battery 42. In particular, FIG. 3 shows a schematic of the connection of three batteries 42 interconnected by two electrical connectors 50 to allow the operation of the bay 40.
A major disadvantage, however, of the batteries 42 is that an electrical connector 50 can be positioned in an undesired position during assembly of the batteries and cause a short-circuit in the electrical circuit connecting the batteries 42, risking damage to the batteries 42. Such an undesired connection position of an electrical connector 50 is shown in FIG. 4, where an electrical connector 50 is connected between the second connection positions B− and B+ of two batteries 42 while another electrical connector 50 is simultaneously connected in the second connection positions B+ and B− of the same two batteries 42. Supply of electrical current to the circuit connecting the batteries 42 would bring about a short-circuit symbolized by 52.
An existing solution to limit the risks of confusion consists of supplying an operator in charge of interconnecting the batteries 42 an assembly schematic of the batteries 42 or an assembly template. However, the risk of confusion in positioning an electrical connector 50, as well as the assembly time of the electrical connectors 50, are too high.
It is also known to the person skilled in the art that errors in connecting electric devices can be avoided by means of connection devices that prevent mismating. What is meant by the term “connection device that prevents mismating” is a connection device including means making it possible to prevent the connection of the connection device in an undesired connection position. To allow them to prevent mismating, such devices comprise mechanical members such as formed or positioned fingers, pins, notches or a combination thereof. However, these connection devices are specialized and costly. Moreover, such a solution for avoiding mismating of the connection positions does not make it possible to avoid connection errors if another type of connection device is used, particularly a connection device that does not prevent mismating.
Document WO-A2-2013/182589 describes a device comprising a plurality of batteries interconnected by a connection bar (called a “bus bar”) comprising connection elements the structure whereof is specifically configured to avoid incorrect assembly of the batteries. In particular, each connection element is constructed to cooperate, at one end, with a pole of a battery or an end-of-circuit element and, at the other end, with another connection element so that the connection elements overlap once the bus bar is installed on the batteries. However, such a device necessitates the use of complex and costly connection elements specifically designed for the type of batteries used in the device. Moreover, the assembly of the connection elements to interconnect the batteries is made difficult, increasing the time required for assembling the device.